The Uruk period (ca.

4000 to 3100 BCE) exists from the protohistoric Chalcolithic to Early Bronze Age period in the history of Mesopotamia, following the Ubaid period and succeeded by the Jemdet Nasr period.

Named after the Sumerian city of Uruk, this period sees the emergence of urban life in Mesopotamia.

It is followed by the Sumerian civilization.

The late Uruk period (34th to 32nd centuries) sees the gradual emergence of the cuneiform script and corresponds to the Early Bronze Age.These early city-states have strong signs of government organization (though social stratification is not strongly evident until very late in this period and the beginning of the Early Dynastic Period, beginning around 3100 BCE), evident even in items such as cheap, mass-produced beveled rim bowls which were made to be discarded.

These bowls may have been handed out at community outings, such as large-scale constructions.

The cities grew to cover up to 250 acres (1 km²) and up to 10,000–20,000 people by the end of the period.Periodization is after archaeological layers at Uruk.

Thus, Uruk XVIII–XIV are not part of the "Uruk period" proper but are comprised by the Ubaid period.

The Uruk period proper corresponds to the layers Uruk XIV–IV, with the late phase Uruk IV lasting ca.

3300–3100 BCE.

Uruk III reaches up to 3000 BCE and into the Early Dynastic period (not to be confused with the Ur III period of the 21st century BCE, where the numbering refers to royal dynasties, not archaeological layers).